In one of the stuffiest and most traditional institutions in the country, he walks around with Iron Maiden on his iPod.

Born in Wimbledon to a German mother and Scottish father, he grew up in Edinburgh where he was later recruited into the youth wing of the SNP by The Proclaimers.

And he spends most of his working week in London, where it is his job as the Westminster leader of the SNP to work towards effectively making himself redundant.

But despite the intriguing background and interests, the man himself is quite single-minded when it comes to his job – leading his party in London and representing Scotland’s interests in the matters he is most interested in, such as defence and European and foreign affairs, as well as working for the constituents of Moray.

With a CV which includes singing on a No1 folk music album earlier this year – more colourful than most grey politicians – 42-year-old Angus admitted he is proud of his background and said every part of his life, from London to Berlin, Edinburgh and Speyside, has played a key part in forming the political beliefs he holds dear.

“When people ask my politics, I say I am a Scottish internationalist.

“I’m very much a product of my upbringing and experience of living away from home. I grew up in Edinburgh as a German speaker, and when I finished university I was away for 10 years. I think everybody should live abroad if they can, for the way it helps you see the world.

“That experience of a different language and culture and living in another place was absolutely key in my perspectives and motivations.

“I remember when I was young and we were going around Europe on holidays, people would ask me where I was from and I’d always say Scotland.

“I don’t have a strong connection to one place or one language and culture. We would celebrate Christmas on the 24th for my German family and on the 25th, but I have more of a connection to German people than Germany.

“Then when I lived in Austria for 10 years, a country that has a similar relationship to Germany as Scotland has to England, kind of ‘big brother, wee brother’, I grew to learn to love Austria, and then know Germany better too.

“Nobody would ever mistake the two countries, but there is a similarity in the friendly rivalry and speaking the same language, although they obviously have a more serious recent history.

“In terms of my own political awareness and parties, I remember getting an SNP poster and putting it up in the house for the 1983 elections.

“In the 80s, I remember being involved in protests against the closure of Ravenscraig and Gartcosh, and with Margaret Thatcher in power it was a very politicised environment.

“One of the first times I was here at the House of Commons I saw Baroness Thatcher going to her car and I felt like going up to her and thanking her for inspiring me to go into politics. But how would you explain you were being sarcastic? So I thought better of it.

“If Scotland had been independent back then we would never have had Thatcher and the destruction of the 80s.”

Angus’s Scottish father Struan was an engineer working in London, married to Berliner nurse Anna who worked in St Thomas’s Hospital, right across the Thames from the House of Commons.

Angus was born in Wimbledon but remembers nothing about the place as the family quickly moved back north to Edinburgh, where he grew up.

Having a multilingual household gave him a set view of the world from an early age, and his German granny used to joke about the day he came home talking in German about meeting Herr Wolfe, aka then SNP leader Willie Wolfe.

Aged 15, a tall young man called Charlie Reid – of The Proclaimers fame – gave him a leaflet about joining the youth wing of the SNP and he has been a member since.

But he never thought about entering politics himself and after studying at Aberdeen University, he became a journalist working for the BBC World Service and then Austrian radio.

His belief in Scottish independence grew and absence made the heart grow fonder for Angus, so he moved back to Scotland in 1999 to stand in the first Scottish parliamentary elections.

After losing out, he moved to Elgin to campaign in Moray and was successful in taking the seat, a key historic marker for the SNP, which was formerly held by Winnie Ewing. In the past 11 years, he has grown to love the area, following the fortunes of Elgin City when he has the chance and indulging in a love for whiskies and folk music.

He is also busy as one of the leading figures in his party, running election strategies including the Yes campaign for the independence referendum.

He showed the Record around the Commons and explained what it has taken to get to the top of his party.

“I wasn’t socialised into a party as a child. And in the early 1980s, when the party were polling at less than 10 per cent, the idea of going into the SNP as a career was laughable. Joining was because you believed in something.”

With a strong military history in his constituency, defence issues and the armed forces are high on his agenda.

With RAF Lossiemouth nearby, he got to know it better by spending time with the service through a Commons scheme.

“Parliamentarians can sign up to spend 21 days with one of the services and I was with the RAF in 2002, which was an amazing experience because we were introduced to all of the aspects of the force that people see when they sign up. We saw the different aircraft and the different operations, and I got out to Kuwait and other parts of the Gulf.

“As someone involved in the political part of the deliberations over whether or not to put people in harm’s way, it’s humbling to see how professional they are and how brave their families are.”

Speyside is now a huge part of Angus’s life and one of his pals in Elgin is local superstar Kevin McKidd, the Grey’s Anatomy and Brave actor. And when McKidd was recently putting together a folk album to celebrate music from the Moray area, fiddle-playing Angus was able to recommend some key players from the area and spent several days in the band’s recording house helping out.

That help came in the form of either cooking Thai food for the squad of hungry Highlanders or singing backing vocals. He was just happy to lend a hand and to have contributed to the Save the Children charity project, which went to No1 in the world music charts.

Angus said: “I must confess that I got my fiddle out, but I heard the others play and decided I was best to help in the kitchen and do some backing vocals.

“My musical contribution was limited.

“It was great fun and a very sociable event, which has gone very well.”

Music is one of his greatest passions and his tastes reflect his German and Scottish background, with recent gigs including Scots folk hero Dougie Maclean, heavy metal legends Iron Maiden and German rockers Rammstein.

His cross-continental lineage is also important to his other great interest of the moment – genealogy.

Angus revealed: “I don’t have an extended family in Scotland – there are many of us in other countries but not in Scotland. I recently got into genealogy, which is something I never thought I’d be interested in.

“I managed to trace my father’s side of the family back to Penicuik, where Robertsons ran the post office. I then traced the family to Mortlach, near Dufftown, in Moray, which was fantastic because I didn’t know I had any connection to the area where I now live, and that goes back to the 1770s. So my family came from the only two places where I have ever stood for election.

“On the German side, I traced my mother’s Chambalu family from Berlin back to Alencon in France in 1773, and an apothecary ancestor. The weirdest thing I stumbled upon was that my great-great-great-great-grandfather John Robertson was in the 10th Inverness militia regiment who were posted to defend the coast from Napoleonic attack. At the same time, a relative on my mother’s side was marching across Spain in Napoleon’s army.”

No matter how interested in his past Angus has become, as one of the highest ranking officials in a major political party it’s his job to look to the future.

The increasingly high-profile debate on independence has become big news around the world, and he has been profiled on German TV and is a pal of half-Scottish politician David McAllister, tipped as a future Chancellor.

One reporter suggested Angus would be an ideal choice for a future Foreign Secretary in an independent Scottish government, but he refuses to discuss it or even get that far ahead of himself.

But that’s not to say, with a referendum on the country’s future two years away, he isn’t thinking about what lies ahead.

As much as he loves his job and being in London, he can’t wait for the moment the post becomes redundant.

“My only regret in terms of London is that in 11 years commuting here I have spent so little time outside of this building and not seen more of the city.

“I cannot wait for the opportunity to be working more in Scotland after a successful outcome to the referendum. I have enjoyed my experience at Westminster but it would be great to not commute so far for work.”